Barnacles belong to the crustecea group of arthropods because even though thy resemble mollusks; they are more closely related to shrimp. They are surrounded by a protective limestone covering that helps them remain attached to a surface. Inside of the limestone cover it consists of a head, abdomen, and thorax. It has a variety appendages on the head and abdomen for specialized functions. Relationship to Humans:
Barnacles often stick to many man-made structures like ships. Sme barnacles, specifically the gooseneck barnacles, are actually eaten and considered delicacies in Portugal and Spain. Another barnacle eaten by the Chilean people is the picoroco barnacle. Habitat and Niche:
Barnacles usually take residence in the intertidal zones of bodies of water. (They are also known to live on the underbellies of whales, on piers, and on the sides of a ship.) The strong outer shell allows barnacles to have a sheltered defense "from the elements" (3). Barnacles also live in a varried cluster, and have to compete for space and resoureces. For example, Stellate barnacles are able to cope with dessication, being dry for long periods of time, better than Rock barnacles. This causes an increase in Stallate barnacles near the shore line, while Rock barnacles tend be at lower depths. Predator Avoidance:
As larvae, barnacles are very susceptible to predators since they float around in the water, much like plankton. However, once they are older and attach to a surface, they develop a tough outer shell made of limestone, usually with multiple layers. This shell makes it nearly impossible for most predators to eat adult barnacles. (3) Nutrient Acquisition:
Barnacles are able to gather food by using specially designed appendages that can retract out of the top opening of the limestone covering.
Barnacles are crustaceans that have jointed legs and shells of connected overlapping plates. Instead of crawling after their food, they glue themselves to objects such as ships and wait for food to wash by. When barnacles are under water or when a wave washes over them, they reach out little feathery barbed legs to strain out plankton and absorb oxygen. (8)
Reproduction and Life Cycle:
The life cycle of a barnacle includes two stages, the free-swiming larval stage and the sessile adult stage. Most shallow water species are hermaphroditic, which means that they have both male and female reproductive organs and can therefore cross fertilize through internal fertilization. Adjacent individuals alternate male and female roles over time. The female individual lays eggs inside the mantle cavity shortly after molting. (2) After mating, the fertilized eggs remain attached to the females body. They are then released as juveniles and attach themselves to a surface in their environment. Before a barnacle forms its tough chitin shell, a barnacle is a "free-swimming larva" (4).
The life cycle of a barnacle
Growth and Development: Young barnacles hatch from eggs and develop into free-swimming larvae . They secrete a gluelike substance and attach themselves to a suitable surface, slowly changing into small jellylike creatures. They then secrete layers of calcium carbonate (lime) to form a shell. The barnacle's legs stick out like tentacles from an opening in the top of the shell. At their tips are cirri, feathery appendages that sweep plankton and other food into the mouth. (6) From there they will consume plankton in the water and gain body mass. Integument:
They have a hard shell composed from chitin (the same material of lobsters and insect exoskeletons). They shed their shell when it gets too small for them (7). As they grow very old, barnacles have very tough shells and are hard to be eaten by predators. Baby barnacles are not born with shells, instead thin layers of flesh wrap around the baby after it's born and it becomes the outer shell (3). Movement:
Barnacles are stationary for most of their life. Before they bind to a surface, they use a muscular stalk to pull themselves closer to the surface. Another form of movement is when they use specialized feeding appendages to bring in food floating around them. Barnacles known as "buoy" barnacles secrete a buoyant, foam-like cement that allows them to float with the current. Other buoy barnacles may attach, as well as individuals of other species of barnacles (5). Sensing the Environment:
Barnacles have specialized appendages on their abdomen for sensing the environment. Gas Exchange:
Barnacles have specialized appendages on their bodies that are used for gas exchange.
Barnacles, like other aquatic organisms, do not possess gills. The primary structures involved in gas exchange in barnacles are the mantle and cirri (feathery appendages) (9). Waste Removal:
Barnacles release waste through their top opening of the limestone cover. Environmental Physiology:
Barnacles live in and around bodies of water. Not all barnacles need to be constantly submerged, but need the moisture and nutrients the water provides. The ideal pH level of water for barnacles ranges from 4.0 to 6.5. (3) Internal Circulation:
The internal circulation of a barnacle is an open system, like most crustaceans. The blood, which fill the body, is mainly pumped by the movement of muscles as the body moves around. Barnacles have no clear respiratory organs; however, structures called branchiae are wrinkled additions of the mantle wall which can be recognized as a type of respiratory organ. Chemical Control:
A comprehensive understanding of the neuroactivity and neuroactive substances in barnacles is lacking. However, one study observed the role of peptide hormones in barnacle development. The study showed that some peptide hormones in barnacles delay larval metamorphosis
Barnacle (arthropda: crustacea) Chris Valiente
Classification/ Diagnostic Characteristics:
Kingdom: Animalia
Phylum: Anthropoda
Subphylum: Crustacea
Class: Maxillopoda
Subclass: Theocostraca
Infraclass: Cirripedia
Superorder: Acrothoracica, Rhizocephala, Thoracica (9).
Barnacles belong to the crustecea group of arthropods because even though thy resemble mollusks; they are more closely related to shrimp. They are surrounded by a protective limestone covering that helps them remain attached to a surface. Inside of the limestone cover it consists of a head, abdomen, and thorax. It has a variety appendages on the head and abdomen for specialized functions.
Relationship to Humans:
Barnacles often stick to many man-made structures like ships. Sme barnacles, specifically the gooseneck barnacles, are actually eaten and considered delicacies in Portugal and Spain. Another barnacle eaten by the Chilean people is the picoroco barnacle.
Habitat and Niche:
Barnacles usually take residence in the intertidal zones of bodies of water. (They are also known to live on the underbellies of whales, on piers, and on the sides of a ship.) The strong outer shell allows barnacles to have a sheltered defense "from the elements" (3). Barnacles also live in a varried cluster, and have to compete for space and resoureces. For example, Stellate barnacles are able to cope with dessication, being dry for long periods of time, better than Rock barnacles. This causes an increase in Stallate barnacles near the shore line, while Rock barnacles tend be at lower depths.
Predator Avoidance:
As larvae, barnacles are very susceptible to predators since they float around in the water, much like plankton. However, once they are older and attach to a surface, they develop a tough outer shell made of limestone, usually with multiple layers. This shell makes it nearly impossible for most predators to eat adult barnacles. (3)
Nutrient Acquisition:
Barnacles are able to gather food by using specially designed appendages that can retract out of the top opening of the limestone covering.
Barnacles are crustaceans that have jointed legs and shells of connected overlapping plates. Instead of crawling after their food, they glue themselves to objects such as ships and wait for food to wash by. When barnacles are under water or when a wave washes over them, they reach out little feathery barbed legs to strain out plankton and absorb oxygen. (8)
Reproduction and Life Cycle:
The life cycle of a barnacle includes two stages, the free-swiming larval stage and the sessile adult stage. Most shallow water species are hermaphroditic, which means that they have both male and female reproductive organs and can therefore cross fertilize through internal fertilization. Adjacent individuals alternate male and female roles over time. The female individual lays eggs inside the mantle cavity shortly after molting. (2) After mating, the fertilized eggs remain attached to the females body. They are then released as juveniles and attach themselves to a surface in their environment. Before a barnacle forms its tough chitin shell, a barnacle is a "free-swimming larva" (4).
Growth and Development:
Young barnacles hatch from eggs and develop into free-swimming larvae . They secrete a gluelike substance and attach themselves to a suitable surface, slowly changing into small jellylike creatures. They then secrete layers of calcium carbonate (lime) to form a shell. The barnacle's legs stick out like tentacles from an opening in the top of the shell. At their tips are cirri, feathery appendages that sweep plankton and other food into the mouth. (6) From there they will consume plankton in the water and gain body mass.
Integument:
They have a hard shell composed from chitin (the same material of lobsters and insect exoskeletons). They shed their shell when it gets too small for them (7). As they grow very old, barnacles have very tough shells and are hard to be eaten by predators. Baby barnacles are not born with shells, instead thin layers of flesh wrap around the baby after it's born and it becomes the outer shell (3).
Movement:
Barnacles are stationary for most of their life. Before they bind to a surface, they use a muscular stalk to pull themselves closer to the surface. Another form of movement is when they use specialized feeding appendages to bring in food floating around them. Barnacles known as "buoy" barnacles secrete a buoyant, foam-like cement that allows them to float with the current. Other buoy barnacles may attach, as well as individuals of other species of barnacles (5).
Sensing the Environment:
Barnacles have specialized appendages on their abdomen for sensing the environment.
Gas Exchange:
Barnacles have specialized appendages on their bodies that are used for gas exchange.
Barnacles, like other aquatic organisms, do not possess gills. The primary structures involved in gas exchange in barnacles are the mantle and cirri (feathery appendages) (9).
Waste Removal:
Barnacles release waste through their top opening of the limestone cover.
Environmental Physiology:
Barnacles live in and around bodies of water. Not all barnacles need to be constantly submerged, but need the moisture and nutrients the water provides. The ideal pH level of water for barnacles ranges from 4.0 to 6.5. (3)
Internal Circulation:
The internal circulation of a barnacle is an open system, like most crustaceans. The blood, which fill the body, is mainly pumped by the movement of muscles as the body moves around. Barnacles have no clear respiratory organs; however, structures called branchiae are wrinkled additions of the mantle wall which can be recognized as a type of respiratory organ.
Chemical Control:
A comprehensive understanding of the neuroactivity and neuroactive substances in barnacles is lacking. However, one study observed the role of peptide hormones in barnacle development. The study showed that some peptide hormones in barnacles delay larval metamorphosis
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046513
.
Review Questions:
1. How does a barnacle's development aid its predator avoidance?
2. If barnacles are stationary for most of their life, how are they able to obtain their food?
Sources:
http://www.bigelow.org/mitzi/images/library/Mid-Intertidal/Barn_16.jpg
http://www.asnailsodyssey.com/IMAGES/BARNACLE/PechenikEtAl1998Fig3.gif
Info added to Reproduction section:
2. http://www.britannica.com/EBchecked/topic/118569/cirripede/33752/Importance-to-humans
3. http://a-z-animals.com/animals/barnacle/ (great source if anyone else wants to use it! Lots of info)
4.http://bio.research.ucsc.edu/people/carr/Raimondi%20Reprints/Barnacle%20chapter%20proofs.pdf
Internal Circulation:
http://www.britannica.com/EBchecked/topic/118569/cirripede/33755/Larval-dispersal
Movement:
5. http://www.bogleech.com/barnacles.html
Relationships to Humans:
http://www.chicagotribune.com/sns-travel-spain-eat-barnacles,0,4654401.story
6. http://animal.discovery.com/marine-life/barnacle-info.htm
7.
http://www.whoi.edu/science/B/people/kamaral/Barnacles.html
8. http://library.thinkquest.org/J001418/barnacles.html
9.http://www.seaworld.org/animal-info/animal-bytes/animalia/eumetazoa/coelomates/protostomes/arthropoda/crustacea/maxillopoda/barnacles.pdf
10.
http://bio.research.ucsc.edu/people/carr/Raimondi%20Reprints/Barnacle%20chapter%20proofs.pdf